Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add basic support for FDT to i386 & amd64. This change includes:
1. Common headers for fdt.h and ofw_machdep.h under x86/include
with indirections under i386/include and amd64/include.
2. New modinfo for loader provided FDT blob.
3. Common x86_init_fdt() called from hammer_time() on amd64 and
init386() on i386.
4. Split-off FDT specific low-level console functions from FDT
bus methods for the uart(4) driver. The low-level console
logic has been moved to uart_cpu_fdt.c and is used for arm,
mips & powerpc only. The FDT bus methods are shared across
all architectures.
5. Add dev/fdt/fdt_x86.c to hold the fdt_fixup_table[] and the
fdt_pic_table[] arrays. Both are empty right now.

FDT addresses are I/O ports on x86. Since the core FDT code does
not handle different address spaces, adding support for both I/O
ports and memory addresses requires some thought and discussion.
It may be better to use a compile-time option that controls this.

Obtained from: Juniper Networks, Inc.

A simple rewrite of biossmap.c:

- Do not iterate int 15h, function e820h twice. Instead, we use STAILQ to
store each return buffer and copy all at once.
- Export optional extended attributes defined in ACPI 3.0 as separate
metadata. Currently, there are only two bits defined in the specification.
For example, if the descriptor has extended attributes and it is not
enabled, it has to be ignored by OS. We may implement it in the kernel
later if it is necessary and proven correct in reality.
- Check return buffer size strictly as suggested in ACPI 3.0.

Reviewed by: jhb

/* -> /*- for copyright notices, minor format tweaks as necessary

Slight reorg and added AMD64 support. A couple of the MODINFOMD_* values
that were added to sparc64 and later powerpc, really should have been in
the MI area. But changing that now with insufficient preperation will
just cause too much pain.

Move MD_FETCH() to the MI sys/linker.h file to avoid another two copies
of it.